Two-tone tests measure a non-linear device's response to two input signals of different frequencies, F1 and F2. A fully linear device outputs only F1 and F2, but a non-linear device (or an imperfect linear device) produces spurious products that are combinations of F1 and F2, specifically: ±M*F1±N*F2. These spurious products are either even order or odd order, determined by whether the sum of M and N is even or odd. Creating two-tone test setups to measure very high performance baseband circuits may be challenging. Traditionally, two generators are combined in a resistive power combiner. However, the low isolation of the combiner requires significant resistive padding of the generators to reduce self-intermodulation. The resultant combined signal then requires amplification by a very linear baseband amplifier. Various attempts have been made to address these problems, but existing configurations create new problems.